Interferometric Lithography Beam Width Adjustment for Coherence
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Solution Overview
Problem
Interferometric lithography systems face challenges in achieving desirable fringe contrast across a large image field due to path length differences in interfering beams, limiting their resolution capabilities compared to conventional lens-based systems.
Innovation Solution
The system adjusts the beam widths of first and second beams to ensure mutual spatial and temporal coherence across a full width, using beam width adjusting systems to match path lengths and maintain coherence, allowing for interference fringes to form uniformly across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If non-symmetrical Talbot interferometer schemes are used to achieve higher resolutions, then resolution capability is improved, but fringe contrast across a large image field deteriorates due to path length differences
Solution Approach 1:
The patent introduces beam width adjusting systems that change the spatial parameters of the interfering beams. By dynamically adjusting beam widths and introducing variable optical path lengths through adjustable optical elements, the system compensates for path length differences across the field of view, maintaining equal path lengths for beams traveling different distances to preserve fringe contrast while achieving high resolution
Solution Approach 2:
The patent employs dynamic adjustment mechanisms including adjustable optical elements and variable path length compensators that can be modified during operation. These dynamic components allow real-time compensation for path length variations across different regions of the substrate, enabling the system to maintain optimal fringe contrast across the entire field while preserving high resolution capabilities
2Manufacturing precision
If path length differences are introduced to achieve non-symmetrical interferometer schemes, then resolution is improved, but spatial and temporal coherence of beams deteriorates
Solution Approach 1:
The patent introduces beam width adjusting systems as intermediary components between the light source and the interfering beams. These intermediary optical elements (such as variable optical path length compensators and adjustable mirrors) mediate the path length differences by introducing compensating path length variations that restore equal path lengths, thereby maintaining spatial and temporal coherence while preserving the non-symmetrical interferometer's high resolution capability
Solution Approach 2:
The system dynamically changes optical parameters including beam width, path length, and optical element positions to compensate for coherence degradation. By adjusting these parameters in real-time, the system maintains equal path lengths for interfering beams traveling different distances, ensuring both spatial and temporal coherence are preserved while achieving the desired high resolution
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the formation of interference fringes with consistent contrast and high resolution across a large field, surpassing the resolution limits of conventional lens-based systems, particularly at dimensions of 32 nm L/S, and improving throughput by utilizing the entire exposure field effectively.
Implementation Method 1
first and second beams are mutually temporally coherent and spatially coherent in the region of overlap to form interference fringes
Implementation Method 2
respective path lengths of the beams are matched when they reach the common region to ensure the first and second beams are mutually spatially coherent and temporally coherent
Data Source
AI summary
A system and method are provided for writing patterns onto substrates. First and second beams are directed to converge and substantially overlap in a common region on a substrate. This can be done so that the first and second beams are mutually temporally coherent and spatially coherent in the region of overlap to form interference fringes to define a writing image. A beam width of the first and second beams is adjusted. This can be done so that respective path lengths of the beams are matched when they reach the common region to ensure the first and second beams are mutually spatially coherent and temporally coherent across an entire width of the common region. In one example, the substrate is moved with respect to the writing image, while writing patterns onto the substrate. In another example, the substrate remains stationary.